|Tessa as she appeared in 2000|
|First appearance||"Ghost in the Bedroom" (2000)|
|Last appearance||"The Time Travellers" (2002)|
|Portrayed by||Verity-Jane Dearsley|
|Full name||Tessa Oliver|
|Aliases||Tess, Aunty Tessa|
|Occupation||Student, Member of Parliament|
|Relative(s)||Roddy Oliver, Colin Oliver, Janice Oliver|
Tessa Oliver is a primary protagonist of The Ghost Hunter, played by Verity-Jane Dearsley. Tessa is more fiery and short tempered than her brother, but still cares deeply for William and even risks her life to save him from the Ghost Hunter.
Tessa was born around 1987 to Colin and Janice Oliver. Judging from comments she made about the area and local characters, she had lived in Little Henlock for most of her life. She was thrown out of the Brownies in 1997 and she started attending Beeches School in September 1998.
Meeting William (2000)
One night in spring 2000, Tessa's brother Roddy was awoken in the early hours of the morning by William Povey, a Victorian ghost who informed that he was being hunted by a ghost hunter. Tessa barged into Roddy's room to tell him he was talking in his sleep and to be quiet.
Tessa is further irritated when Roddy offers her a tin of chocolates that turns out to be fishing tackle. Tessa's quest to buy her own chocolate is what leads her to meeting the new sweetshop proprietor, Mrs Croker, who has taken over the role from Mrs Humphries.
Tessa is further pushed to breaking point when someone (William, unbeknownst to her) polishes her new trainers, ruining them. Whilst reading a book and listening to music in her room, William and an invisible Roddy play pranks on her.
After Mrs Justin mistakes William spraying a water hose in the science lab for Roddy acting out, she asks Tessa if anything is going on at home with Roddy. Tessa confronts Roddy about "his" unusual behaviour, when William hits her with a ball, causing her to run in and tell her mother. To prevent this, William thrusts a shoeshine brush into her hands. When Tessa learns more about William, she is more understanding.
It is Tessa who suggests that Mrs Justin may be the ghost hunter due to the unusual volume of jars she is carrying. She is ultimately proved wrong when it is realised that Mrs Justin is in fact making jams for the village fête.
Tessa's newfound concern for William is noticed by her best friend Catherine Adams, who constantly speculates William is the name of a boyfriend. At the fête, Tessa operates a pony riding stall, which she is forced to break away from when Roddy shows her the truth about Mrs Justin's jars. It is Tessa who is leading the pony Roddy and William are riding when their mother takes a photograph of them, attracting the interest of Mrs Croker when it is printed in the local paper due to the semi-transparent figure of William sitting behind Roddy.
Tessa is cheering on Roddy in his basketball match for Austin house, which he ultimately wins. Tessa is out horse riding when Mrs Croker tries to ensnare William in the Oliver's home. She helps Roddy look for him when he goes missing, and her inquisitive nature leads to her taking on a volunteering job at the sweet shop in order to spy on De Sniff. Whilst there, she climbs into De Sniff's van and is lead to Mrs Croker's hideout off the caravan park, taking her father's mobile phone with her. She discreetly tried to hide and telephones Roddy, but is caught and tied up by De Sniff. Ultimately, this saves William, as Mrs Croker goes to look for him at the Oliver's house when he in turn is out looking for Tessa.
Tessa lies to Roddy and tells him she won't return to Mrs Croker's hideout when he is at Chillwood Castle. She cycles down there and is trailed by Catherine Adams, who believes she is meeting a boy. Catherine falls and twists her ankle, but tells her parents she has broken her leg, leading to an angry reaction from Colin and Janice, who also believe she has a secret boyfriend.
Roddy and Tessa warns the ghosts at the Annual Ghost Meeting at Chillwood Castle of Croker's visit, and are initially thrown out by Lord Chillwood, but later proved right. They witness Croker's fall, apparently to her death, from the battlements. After this, they are accepted by the spectral community. William says his goodbyes to Roddy and Tessa and joins the fellow ghosts of Chillwood, and the duo believe that is the end of the story.
- Colin mentions Tessa was kicked out of Brownies "three years ago" in Series 1. This would mean she was kicked out in 1997. One has to be between the age of 7 and 10 to be considered a Brownie. We know she is older than Roddy, who was previously deduced as having been born in 1988. Therefore, being born in 1987 is the most logical guess.
- Series 1, Episode 4, The Hunt for Mrs Croker